Hemodialysis systems generally comprise a console or cabinet which provides both the blood and dialysate handling and processing functions that are necessary for hemodialysis. In prior art systems, the membrane dialyzer is mounted on the console, along with blood conduit set containing the bubble traps of the arterial and venous conduits, and the blood pump segment of the arterial conduit, which is typically of the roller pump type.
Inside of the console, the dialysate handling and processing equipment includes a proportioning system if the hemodialysis system is of the type which mixes a dialysis concentrate with water to form the dialysate. Temperature gauges, conductivity meters, a dialysis solution pump, and other known components for the processing, heating, monitoring, and pumping of dialysate through the membrane dialyzer unit are also provided in the console.
Also a pair of tubular dialysate conduits are provided for connecting the membrane dialyzer with a supply of dialysate, these dialysate conduits being fairly short since the membrane dialyzer is mounted on the face of the system console, or on a pole mounted on or near the system console.
The console also includes the blood handling and processing equipment comprising typically a blood pump, heparin pump, air bubble detector, line clamp, and blood pressure monitors and alarms. This equipment acts upon and/or communicates with the blood pathway inner lumens of the arterial and venous blood conduit sets.
The arterial and venous blood conduit sets are also connected to the membrane dialyzer, as well as being connected to the patient, to provide an extracorporeal blood flow circuit between the membrane dialyzer and the patient. Since the membrane dialyzer is carried on the console during the hemodialysis procedure, the arterial and venous blood conduit sets are typically each about eight feet long, since the relationship between the dialysis chair or bed and the hemodialysis system console is relatively fixed, and access sites on the patient range from the lower leg to the jugular vein. To avoid undue variation of the types of blood conduit sets, most or all of them provide such long tubing.
Such long tubing creates a significant extracorporeal blood volume that causes a strain on the patient's vascular system. Any reduction in extracorporeal blood volume (without an attendant rise in pressure drop) would result in a significant reduction in hypotension of other hemodynamic problems currently endemic to hemodialysis.
Also, typically, the arterial and venous blood conduit sets for hemodialysis are disposed of after one use, or a few uses at most. Thus, the cost of the sets represents a significant percentage of the cost of dialysis. Any reduction in the cost of the arterial and venous blood conduit sets would comprise a significant reduction in the cost of the long term hemodialysis of a patient, since the procedure is performed on a chronic basis, typically three times a week.
In accordance with this invention a modification of hemodialysis systems is provided, in which the length of the tubing of the arterial and venous blood conduit sets can be substantially reduced, by separating the blood processing and dialysate processing equipment into two consoles such that the blood processing equipment can be brought closer (horizontally) to the patient's vascular access, and closer (vertically) to the patient's heart level. This results in a potentially significant cost savings in the disposable sets, since more than a hundred fifty of them are typically used annually by each dialysis patient.
By way of further advantage, a reduction in the length of the tubing of the blood conduit sets reduces the priming volume of the sets, which, in turn, can reduce the loss of blood by the patient in each hemodialysis procedure. Also, at high blood flow rates, the pressures in a set with blood tubing of reduced length can have a reduced pressure drop. This reduces the risk of collapsing blood vessels in the patient, due to excessive suction pressure at the arterial end of the blood conduit set.
By way of further advantage, the pressure monitoring means (pressure transducers) can more practicably brought to the level of the patient's heart, thus eliminating blood pressure reading errors caused by differentials in the height of the patient relative to the height of the pressure monitoring means. The shortness of the tubing and the correct height of the pressure monitoring means allows very accurate blood pressure measurements in the patient's fistula or graft as called for in an ideal dialysis.